Diamond is an unincorporated community in eastern Palmyra Township, Portage County, Ohio, United States. It has a post office with the ZIP code 44412. The community is part of the Akron Metropolitan Statistical Area. Interstate 76 travels near Diamond. The town used to be a stop on the New York Central Railroad, but the stop was abandoned in the early …Diamond is an unincorporated community in eastern Palmyra Township, Portage County, Ohio, United States. It has a post office with the ZIP code 44412. The community is part of the Akron Metropolitan Statistical Area. Interstate 76 travels near Diamond. The town used to be a stop on the New York Central Railroad, but the stop was abandoned in the early 1970s.